DAY 6 Exploring Matrices with Leetcode Challenges

Hello Everyone!

I am Somuya Khandelwal, and today marks Day 1 of Week 2 in my competitive programming journey. After a productive Week 1, I kicked off this week by diving into Matrix problems on Leetcode. Matrices are a staple in programming, offering challenges that test logic, spatial reasoning, and efficient coding skills.

Today's focus was on solving two medium-level matrix problems, each offering unique insights into manipulating and analyzing 2D grids.

What I Worked On Today

1. Valid Sudoku (Medium Difficulty)

   • This problem required me to validate a given 9x9 Sudoku board by ensuring:
     • Each row contains unique numbers (1-9).
     • Each column contains unique numbers (1-9).
     • Each of the nine 3x3 sub-boxes contains unique numbers.
   • What I Learned:
     • Used hash sets to keep track of seen elements for rows, columns, and sub-boxes.
     • Efficiently managed nested loops to cover all cells in the matrix.

2. Spiral Matrix (Medium Difficulty)

   • The task was to return all elements of a matrix in spiral order.
     • Traversed the matrix layer by layer, dynamically updating boundaries to avoid revisiting cells.
   • What I Learned:
     • Mastered boundary conditions and edge case handling (e.g., single row or column matrices).
     • Developed a systematic approach for clockwise traversal of 2D arrays.

What I Learned Today

1. Matrix Traversal Techniques:

   • Handling 2D grids requires precise navigation and careful tracking of visited cells.
   • Problems like Spiral Matrix emphasize managing dynamic boundaries effectively.

2. Optimized Validation Approaches:

   • Using hash sets for row, column, and sub-box validation ensures constant-time checks.
   • Managing memory efficiently is critical when working with larger grids.

3. Importance of Edge Case Handling:

   • Edge cases like empty matrices, single rows, or columns can easily be overlooked but are crucial for robust solutions.

Reflections and Challenges

The Valid Sudoku problem pushed me to think about how to validate multiple conditions simultaneously without repeating work. Debugging overlapping constraints (row, column, sub-box) was challenging but rewarding. The Spiral Matrix problem was equally satisfying, as it required a clear plan for traversal.

Day 1 set a strong tone for the week, and I feel more confident about tackling advanced matrix problems in the future.

Looking Ahead

Tomorrow, I’ll be working on more matrix-based problems, including Rotate Image, Set Matrix Zeroes, and Game of Life. These tasks will deepen my understanding of matrix manipulation and efficient in-place algorithms.

Thank you for following along on my journey! Stay tuned for more updates as I continue to grow and explore the world of competitive programming.